(1) Field of the Invention
The present invention relates to standing poles and particularly to the repair or modification of the structural characteristics of wood and metal poles. Specifically, the present invention relates to the reinforcement of standing poles which have deteriorated or otherwise weakened or damaged portions and, as a result, are structurally unsound. The invention also relates to the modification of existing poles to give them "break-away" characteristics. Accordingly, the general objects of the present invention are to provide novel and improved methods of such character and to repaired or modified poles or other structural members resulting from the practice of said method.
(2) Description of the Prior Art
It is well-known that standing poles, constructed from either wood or metal, will deteriorate with time. This is of critical importance with respect to telephone poles, electrical distribution and transmission poles and steel towers. Wooden standing poles are particularly susceptible to damage caused by weather, insects, birds, rodents and other animals and rot. Steel and other metal poles and towers are particularly susceptible to damage caused by oxidation. Standing poles which have suffered considerable deterioration are structurally unsound and present a safety hazard.
In the past the unsound standing pole was often removed and a new pole was erected in its place. However, before the deteriorated standing pole could be removed the telephone transmission or electrical transmission hardware had to be disconnected and supported in some manner. This required a great deal of time and money in many cases.
Various methods of reinforcing deteriorated standing poles are known in the prior art. One prior repair method involves the positioning of reinforcing trusses around the base of the standing pole. The reinforcing trusses are bound together, and thus affixed to the pole, by metal bands. This method presents numerous disadvantages. One of these disadvantages is that the method does not prevent further deterioration from wood rot, insect damage, rust and the like. Another disadvantage is that a pile driver must be used to drive the trusses into the ground around the standing pole. The need to employ a pile driver prevents the use of this method to reinforce standing poles that are embedded within concrete or are in close proximity to other stationary objects. Rough and remote terrain, typical to cross-country transmission lines, also make this method difficult and expensive to employ. Finally, the resulting structure has a unsightly appearance which may be unwanted in certain residential or recreational areas. The use of trusses on poles which are within close proximity to highway right-of-ways may also result in increased damage in the case of a vehicle impact.
Another prior art pole repair/reinforcing method involves sectioning the standing pole just above the deteriorated area. The bottom portion of the standing pole is removed and replaced with a concrete structure. The top section of the standing pole is then permanently attached to the concrete lower pole structure. This method also presents numerous disadvantages such as, for example, the great difficulty and cost of suspending the top portion of the standing pole while the concrete section is put in place. Another disadvantage is that incident to the enhanced rigidity of repaired pole.
Another prior art method for repairing metal standing poles and towers involves removing the rust and then welding new metal to the structure. This method is expensive and time consuming due to the need for welding and cutting machinery. Also, this method fails to prevent further deterioration, and in some circumstances promotes it.
It is to be noted that there is a trend in highway safety engineering to require poles in proximity to the right-of-way to break-away upon automobile impact. While steel poles having break-away characteristics can be used in new installations, such poles are comparatively expensive. Further, it would be exceedingly expensive to replace existing wood poles with new metal break-away poles.